Molecular robotics represents the ultimate in the miniaturisation of machinery. We shall design and make the smallest machines possible and use them to perform tasks. Applications of molecular robotics systems could help reduce demand for materials, accelerate and improve drug discovery, reduce power requirements, facilitate recycling, reduce life-cycle costs and increase miniaturisation. In doing so it will help address the needs of society and contribute to competitiveness and sustainable development objectives, public health, employment, energy, transport and security. Perhaps the best way to appreciate the technological potential of molecular robotics is to recognise that molecular machines lie at the heart of every significant biological process. Over billions of years of evolution Nature has not repeatedly chosen this solution for achieving complex task performance without good reason. When we learn how to build artificial structures that can control and exploit molecular level motion, and interface their effects directly with other molecular-level substructures and the outside world, it will potentially impact on every aspect of functional molecule and materials design. An improved understanding of physics and biology will surely follow.